From 607f70a5d24d2df9c63861434c4ba1991226ee34 Mon Sep 17 00:00:00 2001

Message-Id: <607f70a5d24d2df9c63861434c4ba1991226ee34@dist-git>

From: Andrea Bolognani <abologna@redhat.com>

Date: Tue, 11 Jun 2019 10:55:03 +0200

Subject: [PATCH] qemu: Fix qemuProcessInitCpuAffinity()

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Ever since the feature was introduced with commit 0f8e7ae33ace,

it has contained a logic error in that it attempted to use a NUMA

node map where a CPU map was expected.

Because of that, guests using <numatune> might fail to start:

  # virsh start guest

  error: Failed to start domain guest

  error: cannot set CPU affinity on process 40055: Invalid argument

This was particularly easy to trigger on POWER 8 machines, where

secondary threads always show up as offline in the host: having

  <numatune>

    <memory mode='strict' placement='static' nodeset='1'/>

  </numatune>

in the guest configuration, for example, would result in libvirt

trying to set the process affinity so that it would prefer

running on CPU 1, but since that's a secondary thread and thus

shows up as offline, the operation would fail, and so would

starting the guest.

Use the newly introduced virNumaNodesetToCPUset() to convert the

NUMA node map to a CPU map, which in the example above would be

48,56,64,72,80,88 - a valid input for virProcessSetAffinity().

https://bugzilla.redhat.com/show_bug.cgi?id=1703661

Signed-off-by: Andrea Bolognani <abologna@redhat.com>

Reviewed-by: Ján Tomko <jtomko@redhat.com>

(cherry picked from commit 5f2212c062c720716b7701fa0a5511311dc6e906)

https://bugzilla.redhat.com/show_bug.cgi?id=1716908

Signed-off-by: Andrea Bolognani <abologna@redhat.com>

Message-Id: <20190611085506.12564-4-abologna@redhat.com>

Reviewed-by: Ján Tomko <jtomko@redhat.com>

---

 src/qemu/qemu_process.c | 7 ++++++-

 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c

index 8b05cef80c..a3b71354e1 100644

--- a/src/qemu/qemu_process.c

+++ b/src/qemu/qemu_process.c

@@ -2382,11 +2382,16 @@ qemuProcessInitCpuAffinity(virDomainObjPtr vm)

     if (virDomainNumaGetNodeCount(vm->def->numa) <= 1 &&

         virDomainNumatuneGetMode(vm->def->numa, -1, &mem_mode) == 0 &&

         mem_mode == VIR_DOMAIN_NUMATUNE_MEM_STRICT) {

+        virBitmapPtr nodeset = NULL;

+

         if (virDomainNumatuneMaybeGetNodeset(vm->def->numa,

                                              priv->autoNodeset,

-                                             &cpumapToSet,

+                                             &nodeset,

                                              -1) < 0)

             goto cleanup;

+

+        if (virNumaNodesetToCPUset(nodeset, &cpumapToSet) < 0)

+            goto cleanup;

     } else if (vm->def->cputune.emulatorpin) {

         cpumapToSet = vm->def->cputune.emulatorpin;

     } else {

-- 

2.22.0